Add ex-ante fork choice test cases

[hwwhww]

Thank @casparschwa @djrtwo for the testing plan: https://notes.ethereum.org/m1upI_XcRpSskeG4UvgNtA?view

Differences:

• I combined Scenario 1 and Scenario 2 since the only difference is Step 4.
• [Adversarial attestations > proposer boost] I just use full attestation instead of exact proposer_boost + 1 votes.

It's still verbose. Will think about refactoring tomorrow.

TODOs:

• spec_configured_state_test probably is not thread-safe and made test_proposer_boost_correct_head failed in CI. Need to check it.
  • sub-PR: import Spec objects for each test case #2755, Update per-test config to be unique per-test in spec_configured_state_test #2765
• Update test generator
  • Either dump PROPOSER_SCORE_BOOST to meta.yaml or try to dump the full changed config. I'm inclined to the former now.
• Update test format
• [DRY] Clean up the test script.
• Add ex-ante "sandwich" cases.
  • sub-PR: Add sandwich test scenarios #2766

[hwwhww]

Discussion: about the test vector release

This PR now sets configuration PROPOSER_SCORE_BOOST:= 0 in some test cases via @spec_configured_state_test decorator. I'd suggest that we release these PROPOSER_SCORE_BOOST:= 0 test vectors separately from the regular test vector releases.

Reasons:

• It is only useful for debugging + clients haven't implemented the proposer score boost feature. These test cases can be removed later.
• It introduces a run-time configuration overridden in clients' test suite. Probably not worth complexity for just this case.

/cc @ralexstokes @casparschwa @djrtwo

[djrtwo]

I'm okay not releasing proposer_score_boost 0. But it's good to just write a helper that allows for creating attestations as a function of proposer_score_boost + 1. This allows us to easily test the boundaries around proposer score boost

(Which is like our tests when score boost = 0 and there is 1 conflicting attstaiton)

[hwwhww]

@djrtwo good points. I made test_ex_ante_attestations_is_greater_than_proposer_boost_* cases be tested with minimum attestation participant count such that attestation_score > proposer_score now.

if we can release separately, I won't have to change the test format & do deeper refactoring since half of these cases will be deleted.

[hwwhww]

@ralexstokes @djrtwo

I deleted PROPOSER_SCORE_BOOST: 0 tests from this PR, and created another PR for PROPOSER_SCORE_BOOST: 0: #2767 tests. I suggest that:

1. we only merge this PR to the next release.
2. Generate PROPOSER_SCORE_BOOST: 0 special test vector tarball files from Add test cases with configured PROPOSER_SCORE_BOOST:= 0 #2767 separately.

[casparschwa]

Mostly on formatting consistency

[casparschwa]

Given that we only have tests with boost now, I propose to remove the with_boost naming convention.

Suggested change

	def test_ex_ante_attestations_is_greater_than_proposer_boost_with_boost(spec, state):
	def test_ex_ante_attestations_is_greater_than_proposer_boost(spec, state):